The grades on a physics midterm at Loyola are normally distributed with $\mu = 69$ and $\sigma = 5.5$. Jessica earned a $58$ on the exam. Find the z-score for Jessica's exam grade. Round to two decimal places.
Answer: A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Jessica's exam grade by subtracting the mean $(\mu)$ from her grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{58 - {69}}{{5.5}}} $ ${ z \approx -2.00}$ The z-score is $-2.00$. In other words, Jessica's score was $2.00$ standard deviations below the mean.